People love to see dynamic imagery all around them. The bigger, the brighter, the higher resolution, and the more inexpensive these displays are, the better. Today this translates to digital cinema and immersive virtual reality systems that provide a realistic visual experience. While the computational power necessary to make these systems a reality is widely available today, the required very high-quality displays are not.
A display generally consists of one of more light sources, and a method of spatially modulating the light. For example, many displays have one or more light sources (such as an LED, Laser, High Pressure Mercury lamp, Xenon Lamp, etc.), and one or more spatial light modulator(s) such as an LCD chip, LCOS chip, micromechanical mirror chip (such as the Texas Instrument's DLP), some number of lenses and/or mirrors, etc. Other displays are emissive and effectively have a light source at each pixel, such as plasma or LCD panels.
Some projection displays (“projectors”) use one, or a plurality of moving mirrors or an equivalent way to steer light. The mirror moves in time, steering the light spatially. The light source is then modulated in synchrony, so that each target location receives different amounts of light. This type of projector is often built with lasers. If the movement of the light is sufficiently rapid, then the eye does not realize that a beam is being rasterized.
Other types of displays include CRT display projectors, which modulate an electron beam, which thereby converts into modulated light. In other cases the screen, or regions very close to the screen, are patterned. Changes in the pattern selectively block or allow light such as you might with patterned liquid crystals.
In general the display types currently available include liquid crystal, plasma, DLP, Laser, LCOS, and others. All these displays exhibit different kinds of in-factory and post-factory-introduced defects. Thus, there is a need to provide the best quality display a user might want given a given display's capabilities. The type of correction required often depends on the environment of the display such as the ambient lighting surrounding the display, or its positions amongst a plurality of displays. To this end, reference is made to U.S. Pat. No. 6,456,339, entitled SUPER-RESOLUTION DISPLAY by Rajeev J. Surati, et al., the teachings of which are expressly incorporated herein by reference. As described further below, this patent describes a novel approach for seamlessly stitching together the projected image derived from a plurality of projectors, each handling a portion of the overall image fed from a source (a PC for example). A camera that monitors the overall image, feeds information back to the PC and its onboard image processing applications, and is used to appropriately arrange, align and smooth the individual, overlapping images from the adjacent projectors. This produces an overall image that is properly aligned and substantially uniform in color and intensity. However, further improvements to the image quality in this arrangement are particularly desirable.
The state of the art in multiple-projector displays is well summarized by Practical Multi-Projector Display Design by Majunder and Brown, © 2007, published by A. K. Peters. In that book, Majunder and Brown discuss the various ways to find ways to modify the source images going into a projector, so that they look perfect on a screen. Those modifications include warping and mapping the color and intensity of a portion of the image to a different color/intensity so that the result appears uniform (or nearly so). Majunder and Brown focus on the numerous ways to calculate the warping or the quality functions to maximize in order that a multiple projector system appears uniform to the eye. However, neither they nor any of the many papers they reference actually contemplate changing the coarse parameters accessible in the projector, such as contrast, brightness and lens shift.
While the state of the art in multiple projector displays often modifies the input signal to a projector, factory calibration of individual displays generally modifies only the gross settings on a display without modifying the input signal. Furthermore, when many displays are ganged together, their gross settings are generally not changed to be consistent with each other.
Current systems exhibit numerous disadvantages and operational challenges. The gross settings of ganged-together displays are set individually, and generally not set to match each other. It would be desirable if the ganged-together displays provided a consistent appearance with respect to each other. And, as the properties of the displays drift over time, it is desirable to update those settings to maintain display quality. Some display systems have quality targets which must be met, and not just on the day the system was installed. The operator of these displays would benefit greatly from regular feedback indicating when the quality targets are being met and/or when maintenance is necessary. And, moreover, the operator would benefit from advanced notice of when maintenance will be necessary. The modification of the input signal causes unwanted artifacts, such as resampling artifacts, or a decrease in the dynamic range of the system. It would be desirable to minimize those effects. A change in ambient conditions may affect the operation of the display, and it is desirable to automatically accommodate for those changes. Additionally, ambient changes, such as light falling on the display, may render a brighter display system more desirable, even while permitting reduced color accuracy. It would be desirable if the system could automatically adjust itself. In general, it would be desirable to address a variety of concerns pertaining to display systems.